1. Field of the Invention
The invention relates to a cell for performing optical measurements in an automatic analyzer, and more particularly, to a single cell for an analyzer for clinical chemical analyses.
2. Description
Cells for performing optical measurements are conventionally filled with samples and reagents in the analyzer. Electro-optical analysis is then carried out on the sample-reagent mixture contained in the cell.
Known analyzers use single reaction cells, also called measuring cells, which are placed on a suitable carrier in the analyzer by a mechanical, automatically-controlled transport device. After use, the reaction cells are removed from the cell carrier. In these analyzers, each cell remains on the cell carrier for the entire period of analysis. Transport of each cell to the cell carrier, and its subsequent removal from the carrier, therefore takes place only once. Thus, the risk of a cell being lost during transport is relatively low.
In modern analyzers which attempt to achieve a high number of measurements per unit of time (in correspondingly short cycle times), it is desirable to carry out certain steps of the analysis process (e.g., addition of reagents to individual cells, carrying out mixing movements of the cells, and so on) outside the cell carrier, and to use the cell carrier predominantly for performing optical measurements on the sample-reagent mixtures in the cells. For this purpose, the transport of each cell to the cell carrier and its removal from the carrier, must be carried out a number of times. The transport system must allow each cell to be transported between the cell carrier and the different processing stations. Some analysis systems operate with rotatable cell carriers. Thus, it may be desirable to transport cells even when the cell carrier is rotating. Consequently, the risk of a cell going astray in such a flexible and repeated transport system is correspondingly higher.
For many applications, loss of a cell in the analyzer system is unacceptable. In otherwise extensively automated analyzers, any possibility of cell loss during transport would necessitate visually monitoring the transport of the cells during analyzer operation. This is a practical impossibility.
A cuvette of the above-mentioned type is described in European Patent Application with publication number EP-A- 0 512 368 A2 (see U.S. Ser. No. 08/184,521, filed Jan. 21, 1994). Tests carried out with a cuvette of this type have illustrated the desirability of obtaining improved:
(1) optical properties of the portions of the plane-parallel side-walls and of the bottom of the cuvette used as measuring windows for the optical measurements, and PA1 (2) accuracy in positioning the cuvette within the analyzer system.
The subject invention fulfills the need in the art for a cuvette having improved optical properties and accuracy in positioning.